<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        body {
            background: #000;
            text-align: center
        }

        #c1 {
            background: #fff;
        }
    </style>

</head>

<body>
    <canvas id="c1" width="800" height="600">

    </canvas>
</body>
<script>
    let oC = document.getElementById('c1');
    let gd = oC.getContext('2d');       //图形上下文-绘图用的接口


    //  路径操作-跟ps里的选区一样
    gd.moveTo(100, 100);                    //起点
    gd.lineTo(200, 200);                     //前往哪个点
    gd.lineTo(130, 200);
    // gd.lineTo(100, 100);
    gd.closePath();                     //闭合路径
    gd.strokeStyle = 'red';                   //描边颜色
    gd.lineWidth=10;
    gd.stroke();






</script>

</html>